Wash the celery. Using plastic knives, cut the celery into thirds. Fill each celery stalk with one tablespoon of either peanut butter or cream cheese. For the wings, gently push 1 pretzel into the filling, running parallel to the length of the celery stick. Do the same on the celery's other lengthwise side. Arrange the raisins or currents as the eyes, nose and mouth. For antennae, push the slivered almonds or mushroom cap into filling. If using mushrooms, arrange the spaghetti-like mushroom tips upward, like an antenna.